No abstract

No abstract

Resumo Nas últimas décadas a geração de resíduos de construção civil (RCC) tornou-se um fator relevante em todo o mundo. Dessa forma, é cada vez mais importante o reaproveitamento desse material, sobretudo em obras de grande consumo, tais como as obras rodoviárias. No entanto, a aplicação desses resíduos depende do conhecimento das propriedades químicas e mecânicas do material. Entre esses parâmetros destaca-se que a susceptibilidade à quebra do grão é de fundamental importância. Isso porque esse parâmetro influencia diretamente no comportamento do material através da resistência e da permeabilidade. O presente trabalho avaliou a quebra do grão em RCC induzida pelo processo de compactação através da aplicação das energias normal e modificada. Para isso o material foi dividido em frações com granulometrias diferentes. Dessa forma, foi analisada a influência da energia, do tamanho do grão, da mineralogia, do teor de umidade e da densidade da amostra. Os resultados indicaram que a ocorrência da quebra do grão está diretamente relacionada com a constituição mineralógica, observando-se que a maior fração estudada foi aquela que sofreu a menor quebra dos grãos. Adicionalmente, os resultados indicaram que a densidade de compactação da amostra também possui significativa influência no processo de quebra dos grãos.

The problem related to the generation of construction and demolition waste (CDW) is directly associated with its high volume and irregular disposal, especially when such waste is disposed of in landfills. Therefore, it is increasingly important to encourage the reuse of this material, especially in large-scale projects. However, the use of this waste depends on the different constituent materials, which show a wide variability. Within this context, the objective of this work was to study the mechanical performance of construction and demolition waste over time aiming at the use in pavement support layers. Two samples were evaluated, one composed exclusively of construction waste (CDW_1) and the other composed of a soil-waste mixture (S_CDW), with 50% of each material. The tests evaluated the strength of the materials over a curing period from 0 to 224 days. The results clearly indicate an increase in strength and stiffness over time. The CDW_1 samples indicated a more significant increase. The analyses indicated that this behavior occurs due to the effect of self-cementing properties that occur in this type of waste. The results indicate a benefit in terms of strength when using this type of waste either alone or mixed with soil.

Abstract. The Standard Penetration Test (SPT) is often used to estimate the soil parameters for geotechnical design projects, using the N SPT index. However, these estimates are performed based on empirical correlations without any scientific basis. Moreover, the test has a large inherent results dispersion due to the use of different types of equipment and execution procedures. Since the N SPT index depends on the amount of energy that is effectively transmitted to the sampler during the hammer fall, it is fundamental to be able to estimate this energy. Given the importance of estimating the energy that reaches the SPT sampler, an instrumented subassembly was developed in order to simultaneously assess the amount of energy transmitted to the drill rods, at sections just above the sampler and just below the anvil. This paper presents a series of SPT experimental results carried out in two different sites located in the State of São Paulo, using two different equipment set-ups (with manual and automatic tripping mechanisms), enabling the assessment of the top and bottom energy ratio under different conditions. Results show that for hand lifting hammer and automatic trip hammer systems the difference in the energy ratio is not significant. However, the dispersion of the results for the hand lifting hammer system is more pronounced due to execution procedures, equipment and operators.